// https://iai.sh.cn/problem/759
#include <bits/stdc++.h>
using namespace std;
int main() {
  int a, b, c;
  cin >> a >> b >> c;
  int sum = 0;
  for (int i = a; i <= b; i++) {
    if (i % c == 0) {
      sum++;
    }
  }
  cout << sum;
  return 0;
}